An assessment of mechanism-based plasticity models for polycrystalline magnesium alloys

TL;DR

This study evaluates simplified plasticity models for magnesium alloys by comparing them to detailed crystal plasticity simulations, focusing on their ability to capture anisotropy and twinning effects across various textures and grain sizes.

Contribution

It introduces and assesses two- and three-surface plasticity models for magnesium, highlighting their effectiveness in replicating complex microstructural behaviors.

Findings

Two-surface models effectively capture slip and twinning behaviors.

Three-surface models distinguish basal and nonbasal slip contributions.

Models show promise for guiding damage development in magnesium alloys.

Abstract

The objective of this work is to assess computationally efficient coarse-grained plasticity models against high-fidelity crystal plasticity simulations for magnesium polycrystals over a wide range of textures and grain sizes. A basic requirement is that such models are able to capture {\it evolving} plastic anisotropy and tension-compression asymmetry. To this end, two-surface and three-surface plasticity models are considered. The two-surface constitutive formulation separately accounts for slip and twinning, while the three-surface model further apportions the contributions of basal and nonbasal slip. Model identification is based on stress-strain responses for loading along six orientations under both tension and compression. The evolution of overall plastic anisotropy, as well as microscale relative activities of slip and twin systems, is analyzed in detail. The prospects of using coarse-grained plasticity models in guiding the development of physically sound damage models for magnesium alloys are discussed.